More familiar landscapes have been sculpted by surface erosion.还有更多熟悉的地貌是因地表侵蚀形成的。This leaves fertile soil unprotected and prone to erosion.这会让肥沃的土壤暴露在外，使其容易受到侵蚀。Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失....
...the erosion of moral standards.道德沦丧More familiar landscapes have been sculpted by surface erosion.还有更多熟悉的地貌是因地表侵蚀形成的。Abrasion also abets wind erosion.磨损作用也助长了风的侵蚀.As their roots are strong and penetrating, they preven...
许多种蓝藻有固氮的能力.Among the blue - green algae are many species of nitrogen fixation.菌根起着固氮和贮氮的作用.Mycorhizae perform the function of nitrogen fixation and storage.根瘤菌是生物固氮的能手.Nodule bacteria are very good at biological nitroge...